Process for the removal of bitumen from bituminous deposits



gg zsu Patented July 7, 1942.

UHUQO [\Lil'ill'lllllbll (UNITED STATES PATIENT OFFICE PROCESS FOR THEREMOVAL OF BITUMEN FROM BITUMINOUS DPPOSITS Philip'snbkow, Los Angeles,Calif assignor to" Union Oil Company of California, Los Angeles, Calif.,a corporation of California I No Drawing. Application October 18, 1937,

Serial No. 189,754

3 Claims. (01. lea-i4).-

, duce a fluent oil-in-water type emulsion.

- found close to the top of the ground in such 10- calit'ies as Utah,California and Northern Canada, from which a viscous asphalt or malthamaybe obtained. Fluid bitumen, such as'high gravity petroleum, may beremoved from such formations by natural drainage, or by suitablepressure drives imposed by gas or water. Heretofore, no practicalprocess has been developed for. the removal of. viscous bitumens fromdeep subterranean formations. In the case of deposits consisting mainlyof viscous bitumens in conjunction with sand whichcarry no greatoverburden, mining has sometimes been successfully resorted to. vIn thislatter case, the mined oil sands are subsequently treated with a'hydro-'carbon solvent or with aqueous solutions designed to strip the asphaltfrom the sand without emulsiflcation in order to recover the bitumen bymining methods from its natural position. and recovering the bitumen asa fluent oil-in-J free from associated mineral oil matter.

It is an object of the present invention to provide a process for theremoval of bitumen from mineral matter associated with it in its naturaldeposits by a process comprising the formation of water continuousemulsionsof bitumen. It is furthermore an object of the presentinvention facial tension between the bitumen and the water and thesameor other solutes which effect emulsiiication of the bitumen andendow the emulsion with suflicient stability to remain unbroken duringits subsequent mechanical handling or contact with electrolytes presentin the formation or in the water. The invention further resides in h theuse of a small proportion of alkali hydroxides, carbonates, phosphates,silicates, soaps, sulphonated materials, such as Turkey red oil,proteins and carbohydrate materials suchas casein 'or vegetable gums,and alkali salts or tan nic acids, cresol, phenols and the like. Theinvention further resides in the provision for a positive movement ofthe aqueous solution against or through the formation which movement isadapted to scour, remove and emulsify the bitumen. The invention furtherresides in effecting the emulsification at elevated temperatures, or inthe presence of hydrocarbon solvents, designed to soften and/or liquefythe bitumen. The invention further resides in such a process in whichthe emulsion with or without a preliminary treatment to decrease thequantity of admixed mineral matter is broken to recover the bitumen as aseparate phase.

The aqueous solution used in my process should be adapted to depress thesurface tension between the bitumen and water thereby facilitating thestripping of the bitumen from the mechanical handling and agitation. Inmany to provide a process for the emulsification of the bitumen in situwhereby the bitum'en is stripped from the formation whether in situ orremoved water emulsion. It is, furthermore, an object of the presentinvention to provide a suitable emulsifying agent for such a process andalso to provide means forheating, agitation and the like, designed toeffect said emulsiflcation.

The invention further resides in the use of aqueous solutions for saidemulsification which contains solutes aiding in the stripping of thebitumen from the sand by depressing the inter- 55 instances, bothfunctions may be combined in one solute-thus, for example, emulsifyingagents such as sodium oleate, sodium resinate and Turkey red oil-soapboth reduce the interfacial tension and emulsify the bitumen. A surface\tension depressant, such as alcohol, may be used in conjunction with aseparate emulsifying agent, such as sodium naphthenate. The emulsifyingagent may be formed by a reaction bethe bitumen. This type ofemulsifying agent is useful mainly with restricted types of asphalticcrudes having su'ficicnt acids of the proper cannon mime molecularweight to yield an emulsifying agent on reaction with alkali.

With regard to the function of lowering the interfacial tension betweenthe bitumen and water, the quantity of solute need not be limited; thusconcentrations of a few thousandths of a percent are effective andconcentrations of several percent are still more effective. Theconcentration of the solute should be limited however with regard to itsfunction as an emulsify-- ing agent. The emulsifying agent should bepresent in suflicient concentration to effect emulsification of thebitumen and to stabilize the emulsion thus produced against breaking onsubsequent mechanical handling and passage through the formation andagainst contact with such electrolytes as may be present in theformation or the connate water. Concentrations of from 1; of apercent'to 2% or 3% are usually sufiicient for this purpose. Excessiveconcentrations are in most instances to be avoided as wasteful, or asinimical to proper emulsification,

The choice of the proper emulsifying agent, as

well as its proper concentration and the amount and character ofstabilizing agent, must be ascertained by trial. The choice of theconditions are well understood in the art. Asphalts are now emulsifiedfor use in road construction and the conditions of emulsification arepart of the commorrreference in this art. In order to determine theseconditions, it will be desirable to obtain a sample of the formation. Ifnear the surface, this may be done by ordinary sampling as practised inmining methods. If the formation is a deep-lying one, coreing as used inoil well practice can be resorted to. With such samples at hand, theconditions. of temperature, concentration and emulsifier composition canbe determined by trial and the best conditions for stripping the asphaltor oil from the mineral matter and the condition for forming anoil-inwater emulsion of proper stability may be determined.

In general, a suitably adjusted aqueoussolution of the stability andtype described is found to have a relatively fine particle size, whichproperty is of advantage in permitting the emulsion to be transferredthrough porous formations in which the interstices are relatively small.

The emulsification takes place more readily when bitumen is naturallyfiuid or has been rendered fluid by the application of heat or bysolution in hydrocarbon solvents. When an oil sand containing viscousbitumen has been brought to the surface by mining, it may be comminutedand heated directly with the aqueous solution and agitated therewith toeffect emulsification of the bitumen. As an alternative method, the oilsand may be commingled prior to agitation with the aqueous solution witha hydrocarbon solvent, such as kerosene, or the aqueous solution maycontain emulsified therein a light hydrocarbon solvent Deep lyingformations, for instance, those about 3000 feet, are

naturally hot and the asphalt, if not actually thin enough to flow bydrainage, gas or water drive may be sufficiently soft to emulsify if itbe of a nature to emulsify spontaneously. Such deposits may be thosewhich emulsify spontaneously on contact with caustic soda or potash ofproper concentration-that is, of about 0.08% to 0.18%.

When operating on deep deposits reached only by wells, the formation, ifdesired, may be first fluxed with a hydrocarbon solvent. This may beaccomplished by introducing light solvents, such as kerosene or naphtha,into the formation by means of a drive from centrally located wells inconventional manner. In general, the direct application of heat throughthe medium of a heated aqueous solution of the type described suflicesto liquefy and emulsify the bitumen. In this latter instance, theaqueous solution may carry, if desired, more or less emulsifiedhydrocarbon solvent,

In operating on undisturbed formation insitu. I may cause a' positivemovement of the aqueous solution to take place which is adapted to scourthe bitumen from the sands and to provide the agitation necessary foremulsification. The character of the process which can be applieddepends to a large extent on the porosity of the formation. When dealingwith a sufficiently porous formation, I may usea process somewhat akinto a water drive. By sinking a central pressuring well in the formation,and around it sinking several other collecting wells, I may force theaqueous solution, preferably at an elevated temperature, for instance at212 F., down the central well and by means of the applied pressure causeit to migrate to the neighboring collecting wells. In the passage of thehot aqueous solution through the porous sands, the bitumen is strippedfree from the sand and'emulsified in the. form of small discreteparticles surrounded by the aqueous solution. By properly adjusting thecharacter and quantity of the emulsifying agent, this emulsion isrendered sufficiently stable to remain'unbroken during its passagethrough the sands to the neighboring wells and its subsequent mechanicaltransfer to the surface, for example, by means of pumps. Factors tendingto break the emulsion are the intimate mechanical contact with the sandand the admixture of the 7 solution with electrolytes present in theformation or in the whole system. By the addition of sufficient amountpfemulsifying agent, how-- ever, in the form of a soap, or by the use of astabilizing agent in conjunction with the emulsifying agent, forexample, by using a mixture of alkali and casein, I am able to preventthe breakdown of the emulsion under these conditions.

salts present in the formation of well systems,

or an emulsion which would be resolved by the mechanical handling orpumping of the emulslon.

In the case of less porous formations which are permeated by the aqueoussolution only with difficulty, I prefer to use a surging .or'pulsatin'gback and forth motion of the aqueous solution which effects theemulsification of the bitumen .at the outer bounds of the zonepenetrated by the water and subsequently provides for the removal ofthis relatively concentrated emulsionv and its replacement by a freshsolution or at least a diluted emulsion. By this means, the

forward surge. of the emulsifying solution iseffective in causing alimited penetration of the formation, which, when followed by themomentary withdrawal of the solution and repetition of the cycle, causesthe bitumen to be removed in an emulsified form from a graduallyincreasing zone. type of surging motion can be induced by a variety ofmeans, for example, by the action of a pulsating gas pressuring means,such as air ornatural gas on a body of the emulsifying solution lying atthe bottom of the drill hole. In carrying out this process, a heatedaqueous solution of emulsifying and stabilizingagent is introduced intothe well and agitated by means of injection of natural gas or air. Thesurface of the formation is scoured. Gas is then introduced above thewater surface and the water solution is driven into the formation. Undercertain conditions of residual gas pressure in the formations, the watermay then be drained back into the well by releasing pressure andemploying gas lift to withdraw the emulsion. If desired,

a reverse gas drive from surrounding wells may be employed to force theemulsion back into the well. The repeated washing of the formation andstripping the formations may be accomplished.

Various means may be used for heating the aqueous solution and/or theformation. Hot aqueous solution, for example, may be pumped down thedrill hole into contact with the forma- I 2 tion and recycled backto thesurface for further heating; If desired, the system may be maintainedunder pressure to provide for the use of superheated water. This may beaccomplished by heating the solution'under high pressure, such as 300 to1,000 pounds and pumping the solution into wells under the highpressure.

I Live steam may bebrought into contact with men. The emulsion may thenbe removed bypumping or. gas lift.

emulsifying solution on the formation in situ contains but little, ifany, associated mineral. matter and may be broken or resolved directlyto obtain bitumen as a separate phase. Suitable methods of breaking theemulsion comprises the addition of electrolytes, particularly polyvalentelectrolytes, such as 02301:, or breaking by freezing. Other methods mayalso be used for breaking, for

example, substantial quantities, e. g., from 10 to 50%, or methyl orethyl alcohol may be added to the emulsion whereby the bitumen breaksout as a separate phase. The aqueous phase containing the alcohol may befractionally distilled to recover the alcohol and an emulsifyingsolution substantially free from alcohol and suitable for reuse.

In operating onsands which have been brought I to the surface by mining,agitation of the sand with the emulsifying solution may be afforded byany suitable device,-as for example, by means of a paddle mixer, a ballmill, or the like. This agitation should be conducted attemperatures atwhich the bitumen associated with the sand is sumciently liquid toemulsify. Asset forth above, a hydrocarbon solventinay be used duringthe agitation process to liquefy the bitumen by solution rather than byheat.

The emulsionas obtained by the action of the In the case of mined sandswhich have been agitated during the process of emulsiflcation, more orless mineral matter may remain admixed with or suspended in theemulsion. By settling and decantation, as for example, in a Dorr type ofthickener, the greater part of this suspended mineral matter may beseparated from the emulsion. Further separation may also be effected bycentrifuging or filtering the emulsion through fine meshed screens,dilute with further quantities of water, and the like. In breaking anemulsion which contains more or less associated mineral matter, it isdesirable to diminish only the emulsifying properties of the solutionwithout substantially' increasing the interfacial tension between thebitumen and the water. By this means, the sand or mineral still remainspreferentially wet by the water and sinks to the bottom, while thebituminous material separates as a water repellant phase free from bothsand 1 and water. This condition can be realized by the addition ofproperly 'adjusted amounts of breaking agent, for examplecalciumchloride,

.whereby the emulsion is broken while at the same time the tendency ofthe sand to be wet by .the[

water rather than the bitumen is conserved. The process of addingalcohol to break the emulsion, as set forth above, is well adapted forthis purpose.

While the process has been described as applicable to relatively viscousbituminous deposits, such as'asphalts and heavy oils, it is alsoapplicable to removal of the residual oil deposits fromexhausted oilfields. It is -well known that but a fraction of the oil is recovered bypresent methods. The oilformations contain a large percentage of theoriginal oil. The invention here described makes possible therecovery'of additional oil. The fluidity of the 011 makes theemulsification more easy. Many of .the formations are of sufficientporposity to make the use of a water device from centrally located wellsto surrounding wells feasible. The use of a proper emulsifying agentdetermined as hereunder cited will result in the stripping of theformations and theiremulsiflcation inthe water to form oil-inwateremulsions. The emulsion is collected in the collecting wells and removedas by pumping and'gas lift. The emulsions are then broken as describedabove.

The foregoing exemplary description of my invention is not to'beconsidered as limiting since .many variations may be made within thescope of the following claims by those skilled in the art withoutdeparting from the spirit thereof.

I claim:

' 1. A process for removing bitumen such as oil or asphalt fromformations whichcomprises introducing an aqueous solution containing anemulsifying agent into the formation, agitating said solution in saidformation by surging said solution back and forth in the formation toeifect intimate contact of said solution with bitumen in said formation,emulsifying said bitumen by said agitation to form a fluid oil-in-wateremulsion, withdrawing said emulsion from said formation and resolvingthe emulsion to separate the bitumen from the emulsion.

2. A process for removing bitumen such as oil or asphalt from formationswhich comprises introducing an aqueous solution containing anemulsifying agent into the formation, agitating said solution in saidformation by surging said solution back and forth in the formation bymeans of a gas under pressure to effect intimate contact of saidsolution with bitumen in said formation, emulsifying said bitumen bysaid agitation to form a fluid oil-in-water emulsion, withdrawing saidemulsion from said formation and resolving the emulsion to separate thebitumen from the emulsion.

3. A process for removing bitumen such as oil or asphalt fromsubterranean formations which comprises forming a central shaft to saidformation, forming surrounding shafts to said formation, forcing anaqueous solution containing an emulsifying agent down said centralshaft, applying pressure down said central shaft to cause said solutionto migrate to said surrounding shafts and therebi causing said solutionto mix with bitumen in said formation and emulsify the same to form anoil-in-water emulsion, withdrawing said emulsion from said surroundingshafts and separating the bitumen from said emulsion. I

PHILIP SUBKOW.

